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01-09-2013, 01:42 PM | #1 |
Scooby Specialist
Member#: 337170
Join Date: Nov 2012
Location: hesperia, California
Vehicle:2003 wrx silver |
Highly controversal technique for rebuild
I've seen lots of this technique for motocross but none for cars. this is what we like to call, the 'dry' rebuild. dry meaning, no oil! but whoa whoa, you might be thinking 'what?! this guys gonna rebuild his motor with no oil?!' not so fast, what I'm referring to is, the bottom end will have oil/assembly lube and so will the cams/valves, except the pistons and cylinders have no oil. this is done in an attempt to keep from a glazed cylinder to promote the BEST cylinder to ring seal as possible. I've been doing this type of rebuild for years on motocross bikes and my personal bike revs to 13,500rpm with 14.2:1 compression! so don't think this is for the ole mower. I can't tell you with facts if this works to seal better than if you coated the pistons and cylinders with oil but why wouldn't it? because of my recent purchasing of a wrx, I've never gotten into a car motor before besides the rebuild of my ranger so I never really did a dry rebuild on a car. my main worries would be the longer oil passages which would take slightly longer to move oil than my dirtbike would. what is everybody's I lnput? maybe some of you have even done this already. I already know this is going to explode with people freakin out about not using oil but come on now, it's gonna get oil before it gets hot enough to cause damage. now lets get this figured out!
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01-09-2013, 01:58 PM | #2 |
Scooby Specialist
Member#: 330625
Join Date: Aug 2012
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NESIC
Location: MA
Vehicle:2006 WRX WRB |
Is your bike a 2 stroke by chance? If its a 4 stroke and you have oil in the crank case and oil in the cams, you're going to have the oil pump running and you'll have going to the cylinder walls. And if you're just talking about dry assembly of the pistons into the bore, the oil is just added to make it easier to put them in and to make sure they're lubed on the first crank.
Its well documented the best way to break in a 4 stroke car engine, and it must be the best way since F1/NASCAR/raceboats/pro level drag/etc break in their engines. Alternating cycles of high load and high vacuum pulls from low rpm to an rpm limit that slowly gets high as the pulls go on. Pro's do it on the dyno, you can do it in 3rd gear in a large abandoned parking lot, abandoned airstip, closed highway, etc. Engine is assembled with breaking lube, pro guys make their own special concoctions. Oil choice is the big controversy and I've never seen anything mentioning what the NASCAR/F1 engine builders use, I bet we never will. IMO it shouldnt matter, though something with a high zinc content would be preferred and something synthetic. |
01-09-2013, 01:59 PM | #3 |
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hmmm.. im all ears to other peoples opinion and experience
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01-09-2013, 05:40 PM | #4 |
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Vehicle:2005 Super Slow STi CGM |
I install pistons dry. Just a coat of ATF on the cylinders after cleaning and some wd40 on the tapered ring installer.
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01-09-2013, 06:18 PM | #5 |
Scooby Newbie
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01-09-2013, 06:48 PM | #6 |
Scooby Specialist
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I've always assembled my motocross pistons dry as well. Have yet to do it in an auto application. I will on my upcoming build though. What brand tapered ring compressors are you guys using? And are they as much more effective than a clamp style as they seem?
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01-09-2013, 07:00 PM | #7 | |
Scooby Specialist
Member#: 337170
Join Date: Nov 2012
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Vehicle:2003 wrx silver |
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01-09-2013, 07:02 PM | #8 |
Scooby Specialist
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Vehicle:2003 wrx silver |
i dont see what could be different? my 250f engines always come apart looking awesome and always have great compression! i just wish i had hard proof that this was better, but i dont. however, i dont see why it cant hurt to take ALL measures to increase seal and especially on a boosted engine!
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01-09-2013, 07:03 PM | #9 | |
Scooby Specialist
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01-09-2013, 07:33 PM | #10 |
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The point behind this is to keep the top and second ring dry so they wear into the cylinder walls immediately. Those two are what do the bulk of the sealing. So in theory, if the rings are installed dry, they will remain dry but the skirts will get splashed, provided the oil control rings do their job. Regardless of priming the oil system.
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01-09-2013, 08:26 PM | #11 |
Scooby Specialist
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Vehicle:2003 wrx silver |
in a way, but you cant neccesarily "prime" an oil pump in a dirtbike. sure, it could prime itself before it finally fires up if ive kicked it 3-5 times. if i split the cases and all oil has drained from all oil passages, i will rotate the crank to get some juices flowing
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01-09-2013, 09:15 PM | #12 |
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I always use the dry method
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01-09-2013, 09:22 PM | #13 |
Scooby Specialist
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01-09-2013, 09:42 PM | #14 |
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I have and always will use marvel mystery oil(like atf) when installing pistons,back when I was building some of the fastest gsxr and hayabusa motors in the country thats how I did the cylinders and the performance spoke for itself.
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01-09-2013, 10:07 PM | #15 |
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well, looks like thats working for you! my dad gave me his busa after he crashed it and quit. i decided to get rid of it too and got me a f250 as straight across trade. pretty sweet deal! just curious, what 1/4 were they doing?
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01-09-2013, 10:27 PM | #16 |
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01-09-2013, 11:10 PM | #17 |
Scooby Specialist
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01-09-2013, 11:11 PM | #18 |
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I mean, as soon as you crank the engine the sleeves get oil!
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01-10-2013, 04:03 AM | #19 |
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I've always used a light coating of two stroke oil on the cylinder wall of all my mx rebuilds, two and four stroke. If you follow the proper break in procedure everything will seal without problem.
Back in the day when mx cylinders were cast I'd read several articles, (way before internet), that supported a bike broken in hard and fast would be a faster bike. I would assume that also applies to plated cylinders. Only difference, back then if you foo'bared a top end job you simply went to the next size, today if you mess up it's a $500 cylinder. |
01-10-2013, 12:09 PM | #20 | |
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01-10-2013, 04:07 PM | #21 |
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I'm not for or against at this point. Still thinking about it.
What I'm wondering is the longevity. In your situation you're refreshing something like once or twice a season. For our typical customer they are looking at rebuild once or twice a lifetime. What I would like to know is while I can see that it would mesh the walls and rings very quickly what are the long term aspects? |
01-10-2013, 04:47 PM | #22 |
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But the sleeves/cylinder walls aren't pressure oiled, are they? I guess if the rods are notched to spray the cylinders/pistons...or you had oil squirters.
Otherwise the sleeves are splash oiled. So you still have a few seconds of "dry" time to seat the rings. Or I'm missing something, which is very possible. |
01-10-2013, 05:15 PM | #23 | |
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They would be dry until the engine built oil pressure which you should always do before you fire it. |
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01-10-2013, 05:20 PM | #24 | |
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Quote:
after a couple times, or a trans fail, 90-95% would have to call it quits putting 5k + labor each time into a 25-30k car probably only worth 15k in good condition at the time of it blowing |
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01-10-2013, 05:47 PM | #25 | |
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